Intermediate Overrun Brake Band; Vacuum Modulator Assembly; Vacuum Modulator Seams And Seal; Cross Section Of Vacuum Modulator - Pontiac Grand Prix Service Manual

TURBO HYDRA-MATIC TRANSMISSION M-38
7G-39
8092, drive new bushing flush to .010" below seal
counterbore surface.
NOTE: Notches in bushing should be toward front of
extension.
INTERMEDIATE OVERRUN BRAKE BAND
INSPECTION
1. Inspect lining for cracks, flaking, burning or
looseness.
2. Inspect band for cracks or distortion.
THREAMD s c u m SEAL
VACUUM C UPPI3 TO LOWER
HWSINO S U M
3. Inspect ends of band for damage at anchor lug or
apply lug.
Fig. 76-98 Vacuum Modulator Seams and Seal
VACUUM MODULATOR ASSEMBLY
INSPECTION
CAUTION: Do not use any method other than human
lung power for applying air pressure, as pressures over
6psi. may damage modulator.
3. Inspect O-ring seal seat for damage.
1. Inspect for any signs of
4.
Vacuum diaphragm leak check (Fig. 7G-99) -
bending or distortion
-
a. Insert pipe cleaner into vacuum connector pipe as
a. main body
On
a flat wrface and
far as possible and check fpr presence of transmission
observe sleeve for concentricity to body (Fig. 76-97).
fluid.
b. If sleeve is concentric and modulator valve is free
within sleeve, modulator is acceptable.
2. Atmospheric leak check
-
a. Apply liberal coating of soap bubble solution
(available at 5c
-
10c store) to vaculim connector pipe
seam, crimped upper-to-lower housing seam and to
threaded screw seal (Fig. 76-98).
b. Using a short piece of rubber tubing, apply air
pressure to vacuum pipe by blowing into tubing and
observe for leak bubbles.
c. If bubbles appear, replace modulator.
I
7MODULATOR CAN
I
MODULATOR
SLEEVE
ROLL MODULATOR O N FLAT SURFACE TO DETERMINE IF THE
SLEEVE IS CONCENTRIC TO THE MODULATOR CAN.
IF THE SLEEVE IS BENT.RUNOUT WILL BE VISIBLE.
b. If transmission fluid is found on pipe cleaner,
replace modulator.
NOTE: Gasoline or water vapor may settle in vacuum
side of diaphragm. If this is found without presence of
transmission fluid, modulator should not be replaced.
5. Bellows comparison check -
a. Install known good modulator on either end of a
comparison gage (Fig. 7G-100) and install modulator
in question on opposite end.
b. Holding modulator in horizontal position, bring
them together under pressure until either modulator
BELLOWS
Fig. 7G-97 Checking Conckntricity of Sleeve
Fig. 7G-99 Cross Section of Vacuum Modulator